<30MB/s Read speed

[Donga120]

Tranferring to my NAS, my 3TB Fusion drives barely gets above 30MB/s, transferring from the same computer but with a USB3.0 it hits over 100MB/s with a Cat.6 cable so it's definitely not my network or wiring. I'm sure it use to be much better, anyone experienced this? It's a Late 2015 5k model.

I've tested and writing to my iMac from a USB 3 in it hits over 140MB/s, but writing to the USB from the iMac hits about 20-30MB/s again.

 

[Howard2k]

Tranferring to my NAS, my 3TB Fusion drives barely gets above 30MB/s, transferring from the same computer but with a USB3.0 it hits over 100MB/s with a Cat.6 cable so it's definitely not my network or wiring. I'm sure it use to be much better, anyone experienced this? It's a Late 2015 5k model.

I've tested and writing to my iMac from a USB 3 in it hits over 140MB/s, but writing to the USB from the iMac hits about 20-30MB/s again.

I'm not sure how it's definitely not the network or wiring. What else could it be?

Can you provide a clear summary of the set up. Which devices are you talking about, what are they connecting with etc.

 

[Donga120]

I've tested from the the Router > Cat6 > Synology. I've tested 3 different Cat6 cables on 2 iMacs and 1 Laptop, all give 100MB/s. Every test is fine apart from the iMac with the fusion Drive. Also note Wi-Fi is disabled.

iMac with a USB 3.0 in the rear > Cat6 > Synology and you get 100MB/s
iMac Fusion Drive >Cat 6 > Synology and you get <30MB/s


See screenshots below: (Film off the Fusion Drive on the iMac. Cat6 straight into Router > Synology)

(USB 3.0 in the back of the iMac. Cat6 straight into Router > Synology)

 

[Howard2k]

Thanks. That's a little clearer, I think.

So your iMac's internal drive to the NAS is dog slow, but the same iMac's USB 3 attached external drive is fast to the NAS. That's it in a nutshell right? Everything else is the same between the two scenarios?

Is it possible that it's an issue with the fusion drive?

I assume any movie will give you the same issue?

Can you get SMART readings from the fusion drive?

 

[Donga120]

Thanks. That's a little clearer, I think.

So your iMac's internal drive to the NAS is dog slow, but the same iMac's USB 3 attached external drive is fast to the NAS. That's it in a nutshell right? Everything else is the same between the two scenarios?

Is it possible that it's an issue with the fusion drive?

I assume any movie will give you the same issue?

Can you get SMART readings from the fusion drive?

Exactly right. I’ve ran first aid on the drive, Its freshly installed MacOS latest version. I did notice after I removed some stuff and got below 100GB of used storage, it transfered at 100MB/s, presumably because it was now stored on the 128GB in-built flash, but even so the mechanical HDD should not be that slow. Tried multiple movies and same scenario. Not had a proper look at any SMART info on the drive yet.

 

[Wando64]

Are you sure that you are comparing Apples with Apples?
If you are transferring large volumes of data, this will certainly come from the HDD part of the Fusion, hence the slow speed.
Whereas, when you tested with the USB connection perhaps you focussed on a small amount of data that was already stored on the SSD? (Or at least in part)

Just something to think about.
[doublepost=1545382812][/doublepost]

ut even so the mechanical HDD should not be that slow.

When I uncoupled my Fusion drive, I found that my HDD works at approx 50MB/s to 70MB/s so I agree what you are seeing is quite slow even in this scenario.

 

[Donga120]

Are you sure that you are comparing Apples with Apples?
If you are transferring large volumes of data, this will certainly come from the HDD part of the Fusion, hence the slow speed.
Whereas, when you tested with the USB connection perhaps you focussed on a small amount of data that was already stored on the SSD? (Or at least in part)

Just something to think about.
[doublepost=1545382812][/doublepost]

When I uncoupled my Fusion drive, I found that my HDD works at approx 50MB/s to 70MB/s so I agree what you are seeing is quite slow even in this scenario.

Definitely comparing Apples with Apples. The only difference in the test is the source of the file. Its 1 big file, also the same file. The USB proves that its not a networking error as it achieves full speed.

 

[pjny]

Hi I am having the same issue with usb c on mojave. 20-30 mb/second transfer speeds to samsung ssd (USB-C to USB-C) or importing images from a 300mb/second sony sd card to writing to an external 7200rpm drive.